These are useless players that are not going to be needed for the new user team that takes their place.
The whole point is that when these teams are taken over, a new team is generated for them and the old players will be automatically retired.
Sure, but it just looks wrong to have these huge rosters. And I suppose it's a very, very minor practical issue if you're a new team having to scout a bot.
If the draft processing that the BB's run did a little extra subroutine that went something like:
if (team is bot) then (delete three random players)
... that might not be a bad thing.